Questions tagged [integer]
For challenges involving the manipulation of integers.
9
votes
24answers
892 views
Multiplicative undelta
Let us define the "multiplicative deltas" of values \$[\; a_0, \cdots a_N, \;]\$ as:
$$
[\; a_1 / a_0, \cdots, a_{i+1} / a_i, \cdots, a_N / a_{N-1} \;]
$$
The reverse operation - namely "...
13
votes
16answers
775 views
Length of a UTF-8 byte sequence
Determine the length of a UTF-8 byte sequence given its first byte. The following table shows which ranges map to each possible length:
...
15
votes
9answers
581 views
Stagger, stack, sum
Inspired by this Stack Overflow question.
The challenge
Input
An array of square matrices containing non-negative integers.
Output
A square matrix built from the input matrices as follows.
Let \$...
26
votes
18answers
3k views
Make them sum to 10,000
We've recently reached the threshold of 10,000 questions on PPCG. Hooray! Let's celebrate this with a simple challenge.
Input
Two integers \$A\$ and \$B\$, both in \$[1..9999]\$, such that \$A+B<...
-1
votes
1answer
105 views
Every positive integer can be written as the sum of 3 palindrome integers. Wha'ts the largest possible palindrome integer for each integer n? [duplicate]
Let n be a positive integer then n = a + b + c for some a, b, and c that are palindrome integers. What is the largest possible integer ...
17
votes
18answers
3k views
Longest Repeating Subsequence of a Single Digit
Challenge:
Given a positive integer, output the longest single-digit subsequence that occurs at least twice, AND has boundaries of another digit (or the start/end of the integer).
An example:
Input:...
10
votes
7answers
609 views
Whose neighbours are hostile?
Introduction
For the purposes of this challenge, we will define the neighbours of an element \$E\$ in a square matrix \$A\$ (such that \$E=A_{i,j}\$) as all the entries of \$A\$ that are immediately ...
28
votes
37answers
4k views
Half, Half Half, and, Half
Consider the following number sequence:
\$ 0, \frac{1}{2}, \frac{1}{4}, \frac{3}{4}, \frac{1}{8}, \frac{3}{8}, \frac{5}{8}, \frac{7}{8}, \frac{1}{16}, \frac{3}{16}, \frac{5}{16}, \frac{7}{16}, \...
16
votes
18answers
4k views
Simplistic Lava Lamp
Introduction:
I think everyone knows what a Lava Lamp is, but in case they do not:
(Image source)
They're basically glass tubes that contain wax in a translucent liquid. The bottom part is heated ...
21
votes
15answers
2k views
Crown hundred crownty crown
I noticed a certain game had a peculiar life counter, which instead of stopping at 999, gained a new digit – the next number was crown hundred or ...
14
votes
15answers
1k views
Missing numbers in arithmetic sum
Challenge
Giving a valid arithmetic sum with some missing numbers, output the full expression.
Example:
...
6
votes
20answers
389 views
Find the \$\left(n^2\right)^\text{th }n\$-gonal number
Given a non-negative integer, \$n\$, yield the \$(n^2)^\text{th } n\$-gonal number.
Further Detail:
The \$x\$-gonal numbers, or polygonal numbers, are also known as the two-dimensional figurate ...
12
votes
11answers
1k views
Codegolf Rainbow : Fun with Integer-Arrays
Introduction:
(Source: Wikipedia)
When we look at a rainbow it will always have the colors from top to bottom:
Red; orange; yellow; green; blue; indigo; violet
If we look at these individual rings, ...
15
votes
21answers
1k views
Fill up to duplicate ranges
Let \$L\$ be a list of positive integers with no particular ordering, and which can contain duplicates. Write a program or function which outputs a list of positive integers \$M\$ (whose ordering is ...
25
votes
15answers
2k views
Toggle some bits and get a square
Given an integer \$N>3\$, you have to find the minimum number of bits that need to be inverted in \$N\$ to turn it into a square number. You are only allowed to invert bits below the most ...
17
votes
34answers
943 views
Calculate power series result [duplicate]
Related: Calculate Power Series Coefficients
Given a positive integer \$X\$ and a max exponent (Also a positive integer too) \$N\$ calculate the result of a power series. Example:
$$X^0+X^1+X^2+\...
18
votes
8answers
710 views
Spiral neighbourhoods
If we take the natural numbers and roll them up counter clock-wise into a spiral we end up with the following infinite spiral:
...
13
votes
12answers
2k views
Small Ramsey Numbers
Background: the Ramsey number \$R(r,s)\$ gives the minimum number of vertices \$v\$ in the complete graph \$K_v\$ such that a red/blue edge coloring of \$K_v\$ has at least one red \$K_r\$ or one blue ...
17
votes
7answers
612 views
Stacked digit staircases
Given positive integers \$w\$ and \$h\$ output \$w\$ columns and \$h\$ rows of text as described below.
The first row begins with 11 0s, the second row with 10 <...
-1
votes
7answers
385 views
Calculate the sum of all odd digits of pi in range [duplicate]
Introduction
In the not so distant future with the AI revolution, we will need a way to solve their captchas to prove we're not humans.
This challenge was inspired by CommitStrip.
Challenge
One ...
7
votes
10answers
520 views
How many bytes is it
This time, we want render the count of bytes in a human readable way to user. Let's write a program (a full one or a function or other acceptable formats) to do this.
Input
An non-negative integer, ...
25
votes
30answers
2k views
Let's design a digit mosaic
Challenge
Given a positive integer \$N\$, repeat each of its digits \$d_1, d_2, d_3, \cdots, d_n\$ a number of times corresponding to its position in \$N\$. In other words, each digit \$d_k\$ should ...
23
votes
29answers
2k views
Replace me by the sum of my cyclic successors!
I have a simple challenge for you this time. Given an array of positive integers A (or the equivalent in your language), replace each entry Ai with the sum of the next Ai elements of A, cycling back ...
16
votes
8answers
553 views
Classify a region by its slope
Definitions
The kth ring of a square matrix of size N, where 1 ≤ k ≤ ceiling(N/2) is the list formed by the elements of the kth and (N-k+1)th rows and columns, but without the first and last k-1 ...
21
votes
39answers
3k views
33
votes
42answers
3k views
Up and down, up and down
Challenge:
Given a positive integer input n, create a vector that follows this pattern:
0 1 0 -1 -2 -1 0 1 2 3 2 1 0 -1 -2 -3 -4 -3 -2 -1 ... ±(n-1) ±n
...
3
votes
0answers
159 views
Make Three from One [duplicate]
Given a single digit integer and a three digit integer, output a mathematical formula that uses only the single digit and a given list of operators to equal the three digit integer.
Input: A one ...
24
votes
15answers
1k views
Modular broadcasting
This challenge is related to some of the MATL language's features, as part of the May 2018 Language of the Month event.
Introduction
In MATL, many two-input functions work element-wise with ...
24
votes
10answers
2k views
Knight Distance
In Chess, a Knight on grid (x, y) may move to (x-2, y-1), (x-2, y+1), (x-1, y-2), (x-1, y+2), (x+1, y-2), (x+1, y+2), (x+2, y-1), (x+2, y+1) in one step. Imagine an infinite chessboard with only a ...
3
votes
2answers
68 views
Generate lowest degree polynomial from sequence [duplicate]
Introduction
A sequence of numbers is passed in as the input. The program has to generate the lowest degree polynomial possible. This was my first programming project in college and it would be ...
13
votes
13answers
1k views
12
votes
8answers
752 views
Digit Occurrences
Input:
A list of integers (which will never contain a zero)
Output:
A list of the same size with counts based on the following:
If the current item is negative: Look at all items before this item, ...
21
votes
16answers
1k views
Interval Notations
Challenge:
Input:
Two integer parameters a and b (where a<b and the difference is at ...
23
votes
15answers
2k views
Not Quite Roman Ternary
Given an integer n ≥ 0 , output it in a non-positional base-3 notation, using digits 139ABCDE… and a 1-character separator. Every digit is a consecutive power of 3 ...
31
votes
33answers
2k views
Digits in their lanes
Input:
A list of integers
Output:
Put each digit (and the minus sign) in its own lane, in the order -0123456789, ignoring any duplicated digits.
Example:
Input:...
30
votes
47answers
4k views
Which Card is it?
Introduction
Long ago, when I used to code card games with usual playing cards, I used to specify a number for each card and call a function with some number to get a card. This somewhat inspired me ...
20
votes
14answers
1k views
Is this a truncated triangular number?
Related OEIS sequence: A008867
Truncated triangular number
A common property of triangular numbers is that they can be arranged in a triangle. For instance, take 21 and arrange into a triangle of <...
11
votes
3answers
815 views
Crazy but Rational Bases
We have many challenges based on base 10, base 2, base 36, or even base -10, but what about all the other rational bases?
Task
Given an integer in base 10 and a rational base, return the integer in ...
12
votes
5answers
173 views
Reduced Factorization Leader Changes
tl;dr: Output the values where the reduced prime factorization leader changes.
Every positive integer has a unique prime factorization. Let's call the reduced prime factorization just the list of ...
15
votes
19answers
1k views
Make Zero From First 'n' Numbers
Challenge
The challenge is to write a code that takes a positive integer 'n' as an input and displays all the possible ways in which the numbers from 1 - n can be written, with either positive or ...
14
votes
9answers
1k views
Find The Local Maxima And Minima
Definition
The maxima and minima of a given function are the largest and smallest values of the function either within a given range or otherwise within the entire domain of the function.
Challenge
...
32
votes
8answers
786 views
Can square tree rings be generated from primes?
Apparently yes! In three easy steps.
Step 1
Let f(n) denote the prime-counting function (number of primes less than or equal to n).
Define the integer sequence s(n) as follows. For each positive ...
28
votes
8answers
2k views
Find number of ones to get a number using + and *
Introduction
Your goal is to find the least number of ones you need to add or multiply together to get the input value.
Input
One positive integer N.
Output
The smallest number of ones that must ...
14
votes
4answers
877 views
Bottom part of the Hourglass
Challenge:
Input: Three integers: bottom-edge length; starting amount of grains of sand; index
Output: Output the state of the bottom part of an hourglass at the given index, based on the given ...
19
votes
17answers
2k views
Find Integral Roots of A Polynomial
Challenge
The challenge is to write a program that takes the coefficients of any n-degree polynomial equation as input and returns the integral values of x for which the equation holds true. The ...
18
votes
12answers
2k views
Olympic Rings Sequence
Challenge:
Given an index integer n, either output the n'th item in this sequence, or output the sequence up to and including ...
24
votes
61answers
3k views
The Non-Zero Digital Product Challenge
Originally the Multiplicative digital root
Challenge
Basically do what the title says
Method
Given a positive integer 1 <= N <= 100000000 through one of our standard input methods, multiply ...
12
votes
14answers
1k views
Minimise the count of prime factors through insertion
Given two positive integers A and B, return the position p that minimises the number of prime factors (counting multiplicities) of the resulting integer, when B is inserted in A at p.
For example, ...
16
votes
33answers
2k views
Find the largest number of distinct integers that sum to n
The Task
Given an input positive integer n (from 1 to your language's limit, inclusively), return or output the maximum number of distinct positive integers that ...
26
votes
18answers
2k views
Am I a 'Redivosite' Number?
Redivosite is a portmanteau word invented for the sole purpose of this challenge. It's a mix of Reduction, Division and Composite.
Definition
Given an integer N > 6:
If N is prime, N is not a ...
